Electromechanical device and telephone system



July 13,1926. 1,592,323

F. ALDENDORFF ELECTROMECHANICAL DEVICE AND TELEPHONE SYSTEM Filed Oct. 17. 1922 9 Sheets-Sheet 1 my '13, 1926. j 1,592,323

' F'. ALDENDORFF ELECTROI IECHANICAL DEVICE AND 'I'ELEPHON I SYSTEI Filed Ot. 17. 1922 S Shee'ts-Sheet z July 13,1926.

F. ALDENDORFF ELECTROMECHANICAL DEvicr; AND TELEPHONE srs'ru Filed Oct. 17, 1922 9 Shoots-Snot :5 A

Al -wan" July 13 1926. 1,592,323

BLECTROMECHANICAL DEVICE AND TELEPHONE sYs'rEu.

F. ALDENDORFF 9 Sheets-Sheet 4 Filed Oct. 17, 1922 WQUDONV July 13 1926.

F. ALDENDORFF CB AND TELEPHONE SYSTEM Filed 061.. 17

9 Sheets-Sheet 5 ELECTROMECHANICAL DEVI July 13, 1926. 1592323 F. ALDENDORFF ELECTROMECHANICAL DEVICE 4m) mnsraona svsrzu Filed Oct. 17, 1922 9 Sheetg-Sheet 6 July 13 1926.

- F. ALDENDORF'F YEYLECTROMECHANICAL nsvxcs AND TELEPHONE SYSTEI Filed Oct. 17. 1922 9 Sheefs-Sheet v July 13,1926. 1,592,323 F. ALDENDORFF' ELECTROMECHANICAL DEVICE AND TELEPHONE SYSTEM Filed Oct 17. 1922 9 Sheets-Sheet 8 0 000 -000 olooo' July 13, 1926;

F. ALDENDORFF ELECTROMECHANICAL DEVICE AND TELEPHONE SYSTEM 9 Sheets-Sheet 9 Filed 001;. 17. 1922 ill Fatented July 13, 1925.

unirso stares enrsur oFFicE.

FRITZ ALDENDORFF, 0F W'ELIVEEESDGRF, Il'EAI P-J BER-LIN, GERTlEAlFY, ASSIGNOB OF ONE- OF NEW YORK, N. Y.

ntncrnoiuncnanicat DEVICE Aim contentions SYSTEM.

Application filed Gotoher 17, 1922, Serial Ho. 595,18Z'endin.Gerineiiy 'fiotober 1.9, 192-1.

'lfhis invention relates in general to telephone systems and more particularly to electi'on'iechanicel systems in which connections are extended from a preselector or finder trunk to the next trunk ahead through a non hunting group selector, 2. finder switch, and an intermediate trunk.

One f ature of the invention consists in making the finder switches that extend the connections to the next trunk ahead in the form of quick-acting power driven finders. The power employed may be derived from motor, gravity or a spring. The wipers of the finders may be caused to fly straight into a group or" bank contacts in which a calling trunk is located and then to move ep y step until the individual set oi bani: ntacts belonging to the calling trunk is reached. A long, group-marking contact and a short change-over contact is coordinated to each. group of sets of talking and testing hank contacts. i' rwiper stopping magnet and a subsequently operating stepping magnet are both enerergized with the aid a wiper and the bank contacts of ditlercnt length brushed 0 *er in succession by this wiper. The imoelling power spent in setting the quick acting switch I when tlie quiclz acting switch is released.

This restoration is effected by turning the rs of the switch in the same direction .n setting them onto a calling trunk. A further feature of the invention, inaddition to the several features already mentioned,

ate two wire trunlr and means are provided whvehy each ot" a nuinherot practically sineous calls will each start only a single finder, all which finders may .Jcute their line tin ling movements simul- .-eo ill 1.. c said call receiving relays line relays) are interdependent in their acin a novel method grouping the switching apparatus of electromechanical exchanges or or method enables c lines, to he card for say. 50 or 100 J- L is restored A set of relays is feature ot the invention consists exten-dinn existing exchanges. Thisextended, 200 lines without addicial grou fi selectors to the existing equipment. 'Trunlrs are run from the conof the existing equipment to the preselectors Of the additional hoard.

Oth r features of the invention will ap- .pear hereinafter in the description and drawings. I

group selector, two wire trunk lines or intermediate trunks extending roin the group selectors, and a quick acting intermediate trunk hunting finder; and Fig. 5 showing a final. selector or connector consisting of a main voice current switch and two auziiliary switches that steer the wipers of the main switch onto the properwan'ted line.

Figs. 6, 7, S and 9 illustrate a relay equipped with two armatures, one of which is much more easily attracted tharnthe other, I

Fig. 6 being a persp ctive view of the armature end of the, relay, Fig. 7 an end view, Fig. 8 a perspective view of a member which 1 serves to hold the armaturesimposition and to keep them from sticking to each other;

and 9 being a tragmentaryvertical sec tion through the more easily attracted armature and its knite edge support or hearing. 10, 11 and 12 illustrate a novel. of grouping electromechanical e2;- or of extending existing exchanges Flee. method changes wit h out ing equipment; Fig. l0 showin a manner of connecting a trunk to auxiliary switches of connectors and running them to the preselectors of an extensionswitchboard; Fig. 11 illustrating a method of running a sepa rate trunk from each connector to the find-- ers of the extension board, and Fig. 12 show the ordinary contacthenlrs of connectors of one hoerchor'section of a board, to the preselectors or finders of another board. I The selector or switch in Figs. 1 and comprises a frame consisting of a top bridge portion 10, two vertical lateral members all, 11, two inwardly projecting members adding group selectors to the existlit) 10c ing how a two-way trunk may he run from r or bucket 13, 'lorwardl v bent upper bracket l-il, and a rearwardhv bent upper bracket 15. All the parts to are preterably made of a single piece of sheet iroi or metal. Attached by screw; 1:; to the top bridge 1) oi the tr: ine a be brat 17 (Fig. Supported by a iorwardl jecting bracket 18. which torins a the lower bridge :1 ch: which consists ot an iron c at the bottom one having a core in ter. The said core is hollow and a scre is screwed into its bottom end. 20 is hollow at its top end and 3 bottom bearing of a shaft L1 wh'ch i journalled at the top in the bearing bra et 17. Fixed to the shaft. ill is a rat wheel 2:2 which carries pivots 23 around which an armature 24. is adapted to swing. The one end of the armature (the right hand end in Fig. 1) is normally press ipwaixl et 21 is ed 1 b a spring 25. When the mag'n energized the right hand end 2% it the arms ture is swung down round its pivot 23 and the lett end 26 with its upwardlv extending engaging portions is swung" upward and caused to etl ecta coupling between he wheel 22 fixed to the shaft 521 and the wheel 28 fixed to the bushing: 29. is will appear from Fig. 2 the wheel 29 has ten perforations 30 into any one of which the up i'ardl projecting clutching portions can be forced. Fixed to the wheel. ot the sleeve 29 are two springs 31, 2-32. In the normal position of the switch the upwardl mo jecting clutch member 2? forces thi stain:

01 out or engagement wlth tne some 0. Also fixed to the wheel 28 are two ontact slip rings 33, Si upon which two contact brushes 36 wipe. The contact brushes and are fixed screws 37 38 to a o acltet which is attached to the ti-nine oi the sleeve releasing magnet 39. The

sleeve releasing or starting magnet 29 1;: iiKC-(l b v screws all) to the lateral vertical portion ll oi the frame oi the switch and has an armature ll. pivoted. at 42 which normally engages with an? 7 one oi the teeth ell; hi the wheel 29 and thus prevents this wheel rom rotating. Attached bv screws :i'ii. to the left hand vertical portion 11 or the switch ii 3% is a stepping magnet 45 which has an ture 4-6 pivoted (t 47. The armature an arm #18 whose right hand tree end it a sts ppiii; pawl 49 pivot-all? attached 5.! at 50. really the right hand end or arm l8 pulled upward h a spring through a connecting" member il hen armature 46 is attracted ts arm 4-8 pull: the spring 51 downward and when this spring 51 has executed a certain travel it strikes against an insulating pin 53 and thereby forces a contact spring from, acontaet spring .55.

and from an interrupter for interrupting the current through the stepping magnet When the pawl 49 is in its nori al posh tion as shown its top oblique end bears against an abutment 56 lived by screws to the rearwlrdly extending bracket- 15 1). in this posit-ion the end of the i .1 with a tooth oi the wheel this wheel from turning); (rd rotation of the wheel is pre- JV a pawl v attached to the sleeve 29 are lire... These wipers ea ch consist of two members with split angu ends (30 that'bear against each other who i the; are out of engagement vith banlt contacts 61, but which press against the two opposit surtaces of a bank contact when in engagement therewith. The wipers always rotate in th tion, as viewec .in Fig. 2, is clocl= 'v-.isev Fir to the sha'tt box 64 whicl bore. is made square and the holes in the brushes 69 which are threaded over the square sleeve are also made square. (it

course a square sleeve of insulation is ii 'erposed between the brushes and the middle 3 al sleere. The nnddle llllQ' shaped pornet ions ot each brush are held at a certain dis auce apart by Eij lll llfl rings (36.

condtctcd to each brush 59 by fixed n'ushes 67. Each brush 67 consists o'r' two strips or sprin ig metal which are pressed ther eftcept at their internal free ends i bear against the inner surfaces oi the no shaped middle portions of a brush or wiper Normally the top end of the armature -l engages with a tooth 4-3 of the wheel 25 which is fixed relatively to the bushing an its brushes 59. The wheel normally turned into a position in which it is held by the holding); pawl and the stepping pawl 49 and in which the cloclc spring? in the spring box 6i has a certain tensiln which is suilicicnt, when the arma ure ll is ettracted. to turn the wheel and the brushes completely around the whole banl: of contacts ()1 at a comparativeh high speed. ll hen the brushes reach a certain group of banlt contacts, i. e. a group in which there is a calling line or trunk the magnet 19 is energized as will be more full explained hereinafter and then the engaging portion 27 ot the clutch armature is forced upward. The two members 2? and 27 will at first as a. ruleenter two adjacent openingsSO of e same direction. which direcesa 32s the wheel 2 but the wheel 28 will continue turning until the radial arm, such as 69.,

- between the two said adjacent openings 30 slips over the spring member 27 and the two members :27 and 27 enter the same ope-n ing 30 and thus rigidly couple the wheels 28 and 22 together. The spring in t spring box is then prevented from turni the sleeve 29. with the brushes turthcr relatively to the shaft 21 and the whole rotor vents the rotary impulse, imparted to the rotor by the swinging round of the brushes 59, from carrying the wheel 22 round after the two wheels 22 and 28 have been coupled by the members 27 and 27. hen the brushes 59 have thus been stopped, circuits are closed which have the effect of sending stepping impulses through the magnet 415.

The brushes 59 which had been whirled.

round in a continuous movement by the spring in the spring box are now stepped forward by the stepping magnet until the particular calling line or the bank contact thereof is reached. -Other leasing magnet 89 is dcenergized again and at the same. time, or at a later period, stepping" impulses are again sent through the magnet 15, the magnet 21 being deenergizc'd at this time so that the wheel 29 is turned clockwise until one of its teeth engages with -64 will now be rewound and the 'wipers 59,

which will now be standing nearthe beginning of a group'ot bank contacts, will be,

ready to be whirled around again for the purpose of effecting another connection. The circuits involved in the performance of the above described results will be explained in the description of Figs. 3 and 4.

The contact bank 71' has threerows of bank contacts 72 each and a fourth row of bank contacts 73. For every 'ten bank contacts 72 there are two bank contacts 7 3 one oi which covers practically the same arc of a circle as is covered by nine bank contacts 72 and the arc of the second contact 73 corresponding to that of one contact 72. Hence two contacts 7 3 occupy an are which corresponds to that of ten contacts '72. The bank contacts are held between two arcuate metal members 75 and 76 and three spacing arcuate members 77, 78, 79. The bank contacts are embedded between arcuate strips of Q as; to the down ardly .ot the Contact bank.

circuit changes are now effected byrwlnch the reinsulation. One of the arcuate spacing members as, has two downwardly bent lateral members or parts 80,. 81 with 1113-.

wardly projecting cars 82, 83 by means of whlchthe switch is fixed to t-hepillars or uprurhts 8s 85 of a sw tch rack. The frame "10. 11 of the switch is fined by hollow screws bent parts 80, 81 I The hollow screws 86, 87 are. fixed to the members 80, 81 by means of screws 88, 89. By turning the screws 86, 87 the center or the shatt 21 can be shifted relativclyto the contact bank and this permits of a proper adjustment.

' Instead buildino' up the contact bank c in the'manner described the bank contacts may be held in their proper positions relatively toeach other in a mould and an insulating substance which has a relatively high melting point may be liquefied in the mould or squirted in in a molten state and then be allowed to cool in the mould. The bank contacts willthcn be firmly held in the insijilating material, such as lonarith, when the latter has cooled down and become hard. Contact banks can be built in this way at a low cost. This method of constructing contact banks is explained at length hereinafter.

Referring now to F 3 represents a switch (a: the kind described above. three arcuate rows of bank contacts 7%, 72 70c 72 shown in Figs. 1 and 2 and one row of contacts 73, 73" tacts 7 3 shown in Fig.1. The are occupied by a group of ten contacts 7 2' corresponds to that occupied by one long contact 73 and a short companion contact78";. In Fig. 3

each subgroup or contacts 72 is illustrated as consisting or" three contacts, whereas in reality there are preferably ten contacts 7 2 in a subgroup. The rows of contacts 72*, 72 72 and 73 are wiped over by brushes 59 59", 59 and 59 respectively. The mag nets 39, 10 and 45 shown in Fig. 3 correspond to those, similarly designated in Figs. land 2. 0

The circ ".its and general operation of the system will inn. rated from the following description or the operations involved in the establishing of a connection bet ween two subscribers.

lllhen the subscriber1101 raises his receiver, his'line rela 10S and a tinder starting relay 1053 whichis common to a group it has which corres 30nd to the bank contacts corresponding to the con-- ct subscribers. receives current that flows cut-ofi relay 109, line wire 110, subscribers station 101, line wire 111, armature contact 112 to the positive pole. In this circuit the rel 103 which has a high and a low resistance winding energizes first, and when its armature closes the contact 113 so as to short circuit its high r sistance winding the relay 102 receives sutiicient current to close its contact 11-1 and open its contact 105, the contacts 105 and 114; being controlled by an moved light armature such as in Fig. 6 and the other contacts of the relay 102 being controlled by a second armature such as 3 of Fig. 0 to operate which a strong magnetization of the relay is necessary. By the energization of the relay 103 which is slow to release its armature, a tinder starting contact 115 and a contact-group designating contact 116 are closed. The contact 115 closes a circuit for the finder starting magnet 39. this circuit extending from the negative pole through 115, 11?, contact 118 of a relay 119, starting or releasing magnet 39. resistance 120 to the positive pole.

lVhen the armature 114 of the line relay 102 is closed a current flows from the positive pole through a resistance 121, contact 111, right hand winding of the line relay 102, and this winding serves to keep the light armature of the line relay 102 attractet. If another subscriber calls at this moment his line relay, say 102, will not be energized because the lead 100 through which current is supplied to all the line relays is disconnected from the starting relay 1.03 and therefore also from the negative pole of the battery at the open contact 105 of the line relay 102. Hence for a brief interval other subscribers are prevented from sending a line tinder starting impulse over the starting wire 107.

When the finder starting magnet 39 is energized over the starting wire it closes a locking circuit for itself at its contact 123 and an energizing circuit for a relay 110 at its contact 12 1-. It also closes a contact 125 whereby a strong current impulse is sent from the positive pole over the wire 120, contact 122, 114. right hand winding of the line relay 102 to the negative pole. This strong current impulse magnetizes the line relay 102 sufficiently to cause it to operate its armature springs 127. 128, 129. 130, 131. The line relay, whose contact 122 is now open. is kept energized by a holding current which flows from the negative pole through the right hand winding, contacts 114-, 132, 129. left hand winding of the line relay 108. 110, 101, 111, 112 to the positive pole. The wire 106 is now reconnected through 129 to the common relay 103 and'theretore to the negative pole of the battery so that another subscriber will now be able to send a starting current impulse through the starting wire 1.1'T,'contact 135. wirei136 to the nert finder.

It will be obvious that the partial energization of the line relay 102 and the ensuing full energization of the same through the closure of the contact 125 will take place in a traction of a second so that a second calling subs riber may send in his call practically simultaneously, and even it he calls at exactly the same instant the two calls will be dealt with one after the other, that is to say one call will etiect the starting of one finder and a fraction of a second later the other call will etl'ect the starting of another tinder.

The moment a subscriber calls, the subgroup marking contact 116 of the starting relay 103 common to the subgroup of say subscribers to which the calling subscriber belongs, connects the negative pole to the subgroup designating wire 137 and to the subgroup marking contact 138. Immediately afterwards this designating potential is applied to the contact 138 through the contact 131 of the calling subscribers line relay 102. It will be understood that the subscribers line relays 102 are grouped in subgroups for say 10 subscribers and that all the contacts 131 of the relays of a subgroup are connected to one subgroup designating wire 13'? which is connected to one subgroup marking bank contact 138.

The finder 100, being started by its starting magnet 39 as described, its wipers 59, 50", 59 are whirled round by spring power and when the wiper 59 reaches the long subgroup designating contact 38 the wiper Stopping magnet or clutch magnet 19 is energized by a currentwhich flows from the positive pole through 19, contact 139 of relay 1 1-0, wiper 59, long contact 138, wire 137 and then either to contact 116 or contact 131, or through both of these contacts to the negative pole. On account of the length of thecontact 138 the clutch nagnet 19 has sin'iicient time to energize so as to couple the wipers 59, 59, 59, 59 with the tinder shaft. When this coupling operation is completed the wipers will have reached the short contact 112 which is located at the beginning of the subgroup of bank contacts to which the calling subscriber connected. It will thus be noted that the subgroup designating bank contacts are displaced in the contact bank with respect to the line contacts 72, 72*, 72 in such a manner that the wipers are enabled to stop at the beginning of the subgroup of line contacts in which the calling line is situated. lVhen the wiper 59 makes a pause on a contact 112 the relay 10 is given time to energize in a circuit which extends from the positive pole through 19, 139, 59, 1462. wire 1413, armature contact 14-1, relay 140, off normal contacts-30; 31 which will be closed at this time-to the negative pole." Therelay 1% on energizing cuts'the magnet 19 into its circuit which extends from the positive pole through the contact 14:5, winding 1%0, 30,

31 tothe negutive pole. The energization of the relay 1350 results in the stepping magnet bei g energized by acurrent which lure contact 1 16, l5, interrupter 5 1, 55, conthe negative pole through urinatact 1. to the positive pole. The stepping magnet new steps the wi rs of the finder round 1" Lil thecontact 1 18 1S reached w nch ie'cted through wire 1 19, contact the line relay 102 to the cutis spring 12? of oil relay 109 ml the contect'l lfl 1 the test relay. 1

's reached by the brush 599 51,30; 1-51, 100 59, 1&8, 1 19, 127, 109 to the positive pole. T is relay 150' opens the *uit oi' the stepping 'inaigneheo at the contac 1 17 and the cut--05 relay 109 disconnec hole 0 the battery at its contacts 108 and respectively, while connecting the wireto the cut-oil relay through the ar1nare sol-inn; 152. The relays 150 end 109 re now kept energized through the arma- 4\ i totentilon the test wire 14:9 and on f the connectors. Th calling sub- 101 is norconnected through the wipers of the iii 100 and 'throughthe contacts 1?0, 171 of the test relay 150 to pulse relay 201 helon ing to the group selector, the relay 201being energized by a current th of the batte y' through the left hand Windi; got re cry 201, 170' v 59 bank contact,'wire l 2. 173 17 i, 110, culling subscriber 101,

1 115,176, 1'57, bani: contact, wiper 59*,

111, contact of relay to the positive pole vit is to be noted here that when the rev i he line tinder wus energized,

9, which was previously encontact- 124. receives curec by which it is kept he line 1 er is restored tery The relay 119 at circuits the. starting iis magnet allows its to orop back. In this a v[attire 4 1 is in readiness to i with a teeth as 43 of the wheel 25, when the finder 1S restoredin the o herei after described.

to the first group, s lector ends in the dialling; iniby which we roup selector is caused lace its wipers 20%, 205' onto the bank to con acts of a trunk, 212 213, thatleads to a group of finders 300 allocated to the to the positive pole. \Vhen is energized by a current which flows from the negative pole through L ts the line relay 102 and the positive ure spring 152. 'lherelay 150, byshort *rctuting t part of its 'winding places a flows from the negative pole' of the finder 300.

group of switches to which the Wanted subscriber'is connected. Before the said dialling impulses are sent in, the release relay 214: 18 energized by current which flows through the contact 207 of the energized relay 201, 21% resistance 216 to the positive y'vy o v IX LL. "for ltselt through the contact 218 which reuiainsclosed until the calling subscriber hangs up lns receiver. The dialling group selec' nnpulses sent 111 by the calling subs her result in 111113111565 flowing from the negative pole to 218, back contact 210 which is closed each time the hne relay 1s ,deenerg ized, contact 219 which is kept closed by the ling in'ipulses are being sent in, Wirev stepping magnet 206 to the positive pole of the battery. When the Wipers 20%, 205 have thus been stepped onto the wanted trunk the changeover relay 215 whilst the dialline relay .201 keeps its arniatures continu- .20) belonging to thesubp'roup of trunks that are connected to a subgroup of bank contacts, ot the lrunlr finders 2300 starting relay 240 to the negative pole ot the buttery 'lhe staring relay 23% sends a starting 11n pulse to the starting magnet 39 of the finder 800 through the starting wire 23'? and the moment the finder 300 is Stilltdltsends an impulse buck through the contact 239'and the wire 2&0 which causes the relay 229 to uttract its heavy urinatures and to thus disconnect itseli from the lead 281 which is common to all the relays of the entire group oi trunks connected to all the bunk contacts Before an impulse was 0111 the line tinder 800 over the scribed the relay 229 after i" ener l ion, was kept energizczd b v' ini ti n current from the positive pole through 2&2, 24-3, 2 11, right hand winding oi the re to the n ativepole similarly as in the cuseot the Line relay 102, F1g.

The starting! relay 234- and the relay connect the negative pole or" the battery through their contacts 236 end 24% respectively to the subgroup designating wire 24:5

andto the subgroup designating; cont-act belonging" to the particular subgroup oi interniediute trunks in question. The finder 300 whirls its wipers 59 59 59 259 round and these wipers are stopped at the beginning; oi the subgroup of banlz' contacts in whichthe culling trunk is located. Then lhe reluy214 closes a locking circuit 1 the wipers are stepped onto the calling trunlt and this trunk 212, 213 is extended through the contacts 270, 280 or the relay 250 to the trunk 301, 302 connected to the final FGlGCl'O! 4-00. The o ierations ot the trunk tinder 300 being similar to those of the line tinder 100 it deemed unnecessary to describe them in further detail.

li 'hen the trunk 212, is through the tinder 300 to the trunk 301. the line relay 303 of the connector or final selector is energized by current which [lows from the negative pole through 303, 270, 59 bank contact, wire 281, trunk wire 212,

213 connected wiper 20 1; contact 2N. 221 to the posititve pole. The rel: j 303 on energizing closes its contacts 316, 3 7 and the role relay 3L1 is energized by a current from the negative pole through 316, 314-, resistance 318 to the positive pole. The release relay closes a locking circuit tor itself at the contact 320 and at the contact 3,1 it connects the negative pole to the relay 250, whilst at its contact 321 it closes an energizing circuit for the relay 323, this relay completing a locking circuit "tor itself which extends through armature contact 32% and through the oii' normal contact of the tinder 310. The relay opens its contact and thus prepares the restoring operation or the trunk finder 300 which will be more fully described later.

At. this uncture it must be mentioned that when the group selector 200 left its normal position its oil normal contacts 224, 225 were closed, the contact 221 preparing a restoring circuit for the group selector and the contact 225 short circuiting the changeover relay 215. The change-over relay is decnergized after the first set of dialling impulses has been sent in and the group selector wipers have been set onto the proper trunk. By this means the change-over relay 215 is prevented from being energized again (via 218, 2-15, 217, positive pole) when its short circuiting contact 209 is opened during the sending in of the succeeding series of dialling impulses by which the final selector is caused to move its wipers onto the wanted line. Hence when the second series of dialling impulses is sent in and the contact 211 is opened a corresponding number of times, the line relay 303 at the final selector will allow its armature to drop back at each opening of the contact 211 and a corresponding number of impulses will flow from the negative pole of the battery through 320 327 328 or. the change-over relay which is energized during the dialling impulses, by a current that flows through contact 329 of relay 330, stepping magnet of the tens group designating switch Td to the positive pole. The tens designating switch Tcl marks the particular group of bank contacts onto which the wipers 353,'

354-, 355, 357 of the voice current switch or main switch of the connector 400 is to be set. This marking ot the proper bank contact group is etiected by means oi the arcuate member 358 with its associated bank contacts 359, 360, 361 and the group des ignating contacts 362, 363, 3(3-t. it will be supposed that the wanted subscriber is in a second group of bank contacts, i. e. in the group corresponding to the long contact 363. This being the case, two impulses will be sent through the stepping magnet 352, and the arcuate member 358 will he stepped round so as to connect the negative pole with the two contacts 359, 36(h A circuit is then closed which extends first from the negative pole through 358 and 359 to the brush. and then through the contacts 360, 362 when the brush 357 has been stepped from the contact- 3'70 onto the contact This circuit through the brush extends 'lurther through the wire 371 and the relay 372 to the positive pole, the relay 372 closing the circuit of the operating magnet 374-, and this circuit extending from the positive pole through the interrupter 375, operating magnet contact 376 ot relay 377 contact 373 to the negative pole. The brushes 354, 355, r 57 are now driven forward by the operating magnet 37 1 until the brush 357 has passed over all the designat ng contacts that are connected by the arcuate member 358 to the negative pole, these designating contacts being, in the case under consideration, only the contact 362, so that when the brush 357 leaves the long contact 362 the relay 372 will be deenergized to open its contact 373 and switch otl the operating magnet 37%. iVhile the wipers 353 to 357 are thus being driven forward into the proper subgroup of bank contacts the subscriber may be sending in the last series of dialling impulses. During the pause which ensued before the final se ries of impulses were sentin, the changeover relay 315 was short circuited at the contact 317 so that it closed its contact 332 to energize the relay 330 by a current which flows from the positive pole through upper winding 0t relay 3330, contact 359, arcuate member 358 to the negative pole. The relay closes a locking circuit tor itself which extends from the positive pole through 331, 380, 320 to the negative pole. Hence the last series of dialling impulses results in stepping impulses flowing from the negative pole through 320, 327, 328. 350. through the stepping magnet 381 or the units designating switch U71 to the positive pole. It the last series of dialling'iinpulses comprises three impulses the wiper 382 will. he stepped onto the third units designating contact 383, the other wipers 3841, being stepped onto curved contact strips 386 and 387 respectively. When the relay 372,

iii)

tact 383, 376, 374;, interrupter 375, to they lhe operating magnet 374:

positive pole. now drives forward until the wiper 356 strikes a bani:

contact connected to the bank contact 333 onto which the wiper 382 of the units des-c ignating switch is stepped. W hen the wiper 356 reaches the said bank contact the circuit of the operating magnet 374i is opened at 3'76 on account of a current flowing from the positive pole through 332, 390, 391, 382, 392, 356, relay 377 to the negative pole. The relay 3'77 closes a test circuit at itscontact 393 and a test current then flows through 394:, test relay 395, test wiper 355, test wire 160, contact of the wanted subscribers line relay, cut oil relay 7 or" the wanted subscriber corresponding to 109, positive pole. If the wanted subscriber is free, the test relay 395 will be energized and will close its contacts 396, 397, 398, 399, 400, 401. By closing its contact 396 the test relay 395 establishes the busy condition on the test wire 160 so as to prevent other connectors from connecting to thesame wanted line. At its contact 399 the test relay establishes a ircuit for the ringing relay 347, this circuit extending from the negative pole through the curved contact 37 8, wiper 385, 399, upper winding of relay 3&7 to the positive pole. Ringing current from the ringing generator 346 is thus applied through the contacts 349, 345 and 400, 401 to the wanted line immediately the test relay responds. When the test relay 395 responds it also immediately connects the interrupter 493 to the stepping magnet 381, via 397, 404, 405, 38 i, 386 and the units designating switch is sent by these impulses back into its normal position, the circuit throughthe operating magnet 331 being opened when the wiper 384. and its companion wipers 382,.

reach their normal position. When the circuit of the ringing relay which ex tends through 337, 335, 399 isopened by the wiper r saii'iing its normal position the ringing relay 3%? is closed periodically by the interrupter 411 which sends current impulses through 398, 340 and the lower windinn' oi? the ringing relay 347.

When the called subscriber responds a current flows through the ringing cut off relay this relay then opening; the circuit ot' the ringing relay at 34.3 and closing the I circr it oi an auxiliary release and metering relay 336 at its contact 341. The relay 336 closes a locking cir uit for itself which e2;- ;encs rroin tn s1 1V e r L ire e t i l P *e p0 t e o e l ugh thel at hand winding, contact 338, 320 to the nega the wipers oi the main switch steps the Wheel 22, Fig. 1, round wheel'28 will then .be'prevented tron. r

tive pole, At its Contact 33? the metering relay closes a circuit wh ch extends from the positive pole through the retardation @051 see, 59 295,213, e05, 223, 293, relay 203 to the negative pole. The T relay closes its contacts 297, 298, 299, 299, 298 and thus connects the translator 29'? in the trunk line. The relay 203, which closes a locking circuit for itself that extends through 299, 296, 295 to the positive pole, may also close a'rneter circuit which is not shown in the drawing, but which may extend either through the test wire and test wiper 59 to a meter that is connected in parallel to the cut or: relay 109 ofthe calling subscriber, or through a separate metering; circuit which extends through a separate wiper on the finder 100.

The subscribers can now converse through he repeating coil 297, the calling suber receiving his michrophone feed curthrough the two windings of the line relay 201 and the contact 299 of the relay 203, while the called subscriber receives his inichrophone teed current through the windings of the relay 3&2 in the connector.

Assuming that the calling subscriber-rm places his receiver first, the line relay 29lwill be deenergized and willshort circuit the release relay 214k on contact 293. ll hen the armature of the release relay 21% drops back a restoring circuit is closed through the interrupter 292, contact 293, 22 i, 220, operating inagnet 2O6 to the positive pole.

The operating magnet 206 then rotates the wipers 204, 205 until they reach their nor mal position, when the off normal contacts 22 225' are'opened andthe interrupter 292 is switched oft.

The deenergizationof the release relay 314: also results in the circuit of test relay 150 being opened at 289 so that the relay 250'allows its armatures to drop back and the stepping: magnet oi the line tinder is energized by current iinpul, which ilO'W from the positive pole through 1.7. individual interrupter 55, 54, Contact i i-t3 to the Qliii new negative pole. The stepping; inn

a .d there wil be reinected by turns the shaft 2?. which. memoered, is mechanically tl'iroug h the Slflllllgl' in the sprin, Fig. 1, to the sleeve 29 that car brushes. The sleeve and the brushes at first rotated with the shaft until the wheel 28 is turned intoa position in which t tooth. as 43, nearest to the arn'iul'ure Fig. 1, strihes against this fliliidlinc; further. and then the ratchet wheel the finder will be turned alone so as it) retension the spring in the spring bo =3 Nhen the springhas been telly retei oned tl'ie nieinber 27, Fig. 2, will strnte against the button and will open the oil normal loo contacts 31, $2. see Figs. 2 and e. ll hen the oil normal contacts 30, 31. Fig. 3, are opened 11G .11 By opening the contact he rele 31d opens the locking circuit of 377 and atits contacts opens deenergized through the called s replacing his receiver. The rclu. 314 also connects the interrupter 451 of the tens designating switch. and the operating magnet 352 of this switch thersteps its wipers round until the wiper lands upon the contact 4 53. When wipers 01 the tens designating switch T01 are thus stepped. round, the areuai'e wiper not; connects the negative pole to all ot the long contacts 362, 363. 36% and this "3 in the relay 372 being energized by a current "from the negative pole tl'irough the are ate wiper 358, long contacts, wiper 357 ot the main switch. relay 372 to the positive pole. The operating magnet 31 4. of the main switch then receives current through tne contact "378 of the relay 372 and drives the wipers round until they are restored to their normal position in which the wiper 357 rests upon the normal contact 3. 0. The arcuate wiper 358 will now be standing on all the contacts of its bank except the contact 359. The relay is therefore dcencrgizeil when the wiper 35? reaches the contact 3""0 and an impulse is then sent from the interrupter -60 through the contact lGl. at "T. through 3 and the operating magnet 55:) to the positive pole. This impulse restores the nrcuatn wiper 358 to its normal position in which it stands adjacent to the contact with-- out contacting there"-.v'ith.

The marginal line relays 102. l

3. and

229, Fig. i, are constructed as shosvn in .Figs. 6 to 9. The relay has a light. easily moved armature 5 and a heavy armature 3 both mounted on a hnite edge at one end of its iron limb 2. The lightarmature ii is located in the densest part or the magnetic field produced by the iron core 01" the relay winding 1, while the heavier armature 3 is acted upon by a magnetic field which is not nearly as dense as that which acts upon. the armature 5. By this means the armature 5 is made to respond much more readily than the heavier armature 2-3. To prevent the easily moved armature trcm sticking to the armature 3 a spacing memher is employed which is shown in perspective view in Fig. 5. The two lugs or ears the armature and the two vertic members of the armature The nember is fastened to the light arma screw 8. The point 9 oi this screw enters a cavity in the end of the limb 2 as shown in Fig. 9. The overhanging portions 7 attached to the spacing member serve to hold the armature 3 in its proper p sition on the knife edge as illustrated in Fig. '7.

it will be obvious that several line finders of the kind described above may be interposed in ta 1dr between the calling lines and the numerical switches.

10 to 12 which illustrate circuit armaintain proper aps between the or rangeinents for eitect-ing truik connections between two different exchanges or groups 'ill now be described.

In an exchange equipped with connectors or .iinal selectors whose wipers are set onto the wanted line by means of designating switches (group designating switches and line designating switches) connections intended for another exchange may be established over inter-exchange or trunk lines by means of the designatingswitches. The iniGY-CXClll' trunli's may lead from the bank contacts oi the designating switches of the one exchange to the preselectors or line finders o't the second exchanges. arrangement also constitutes a convc..icnt method of extending existing exchanges. If for example an establishment is provided with an illlllOlIlfllliC board whose ultimate capacity is or lines and it is desired at a later period to install another 50 or 100 lines a second board may be put in, and one or more trunk lines may be run between the two boarts which will give inter-group or inter-exchange connecting facilities. l nstead oi estahlishing the connections with the other exchange through the banks oi the lesig rnating switches the trunk connections may he est. hlished through the main wipers of the final selectors.

Fig. 11 shows an arrangement in which a single trunk ll-76, 1577 is run from the tens designating switch Trl to the preselectors or line finders of another board which is assumed to he ot the type shown in Figs. 3 to In the circuit arrangemmit illustrated in Fig. 11 a separate trunk H7, 478 is run from each tens designating switch T(Z in Fig. 11, are wired at the second board ex- 'nected to another board. 7 scriber is connected through to the trunk actly like the ordinary subscribers lines shown in Fig. 3. I

7 It will be assumed that a calling subscriber has been connected through to a connector oi, the kind shown in Fig. 10 and that this subscriber desires a connection with a line conhen the sub- 301, 302 the-line relay 303 is energized in the manner explained in connection with Fig. 5 and the release relay 314 is then alsoeng ergized, while the changeover relay 315 is prevented from being energized by a shortcircuit thatis closed at 317.

To obtain a connection with the other board the calling subscriber sends in one dialling impulse and this results in one operatingimpulse flowing through the operating magnet 352 over the following path: negative battery pole, 320, 327, 328, 329, 352, positive battery pole. The wipers 452, 358, 470, 471, 472 of the tens designating switch Td are thus rotated one step and the wipers 470, 471, 47 2 land on the bank contacts 473, 474 and 475 respectively, while the wiper 358 remains in contact with bank-contact 490, because it takes two steps to shift it off 490 and onto the bank contact 359. The

wiper. 452 does not reach the arcuate bank contact 451 until it is rotated two steps.

Then the said selecting or dialling im pulse has been sent in, a pause ensues dur ing which the change-over relay 315 (which is energized by current from the negative pole, through 320, 315, 319 to the positive pole) is deenergized by the short circuit closed at 317, and a test circuit is then closed as follows: negative pole, 480, wiper 358, 490, 491', test relay 479, test bank contact 4.73, test wire 492, resistance493, positive pole. It the trunk 47 6, 477 is engaged by a connection established through some other tens designating switch Trl, the potential on the test wire 492 will be too low to energize the test relay 479, and the calling subscriber will receive abusy signal (by any preferred means not shown), but if the trunk is free the test-relay 479 will be energized and it will close its contacts 482, 483, 493 while opening its contact 480. By the direct application of the negative pole to the contact 7433 the positive potential on the test wire 492 is lowered to such. an extent that the;

test relays oi other tens-designating switches whose wipers are subsequently set onto the trunk 476, 477 will not be energized sufficiently b0 attract theirs =ructu1'es.-

When the contacts482, 483 of the test relay 479 are closed as described a current flows from the positive pole through the retardation coil 484, contact 485 of relay 303,

348, 482. 472, 475, trunk wire 476, and then through the line relay of the trunk at the second board, which trunk anclline relay are wired like the subscribers lines shown in 3. The line relay at the second. board nowresponds and this resultsin the connection being extended to'a. group selector or to final selector like that shown in Fig. 10. Assun'nng that the calling subscriber has now been connected through a final selector, he will send in two more series of dialing impulses, the first series operatingtoset a tens designating switch which may be like the one shown in Fig. 10, or like that show 5. The final series of dialling impulses operates to set :1 units designating switch such as Ud at the final selector of the second board and the wipers of the final selector will th n be steered onto the bank cont-acts of the ,wanted linen hen the wanted subscriber a snbscr'ibers meter or the like.

It will be noted that the brushes 353, 354, 355, 356, 357 of the final selector, Fig. 10, have not been a'fiected in any way in establishing a conversational connection through the tens designating switch TcZ that belongs to the final selector in the first board.

If the called subscriber hangs upv first at the end, of the conversation the deenergization of the relay 342 results in the negative pole being applied continuously through' j-it-(l,

to the right hand end of the release re .lay winding, so that the release relay 314 will be short-circuited and caused to close a restoring circuit at its contact 335 which extends from the, negative pole through the interrupter 450, 335, 497, arouate bank contact 451. wiper 452 of the tens designating switch, magnet 352, to the positive pole. The magnet 352 now drives the wipers 452, 358, 470, 471, 472 forward until thewiper 452 reaches the bank contact A final restoring impulse then flows from the nega ive pole through 460, 461, 453, 452, 352

to the positive pole and this rotates the winers into their normal position. While the wipersoi' ti designating switch are thus rotated forward until they reach their normal position the relay 449 is kept energized. by a current from the negative pole through 493,

479,470, arcuate contact 497 to the positive pole and the negative pole is thusakept disconnected at 480 from the arcuate wiper358 so as to prevent the brushes353-357 of the main switch of the final selector from being moved by currents sent through the contacts 3539. 860, etc. to the operating magnet 37st and to the relay 372 which would switch on the magnet 37+; through its contact 373.

The restoration of the other switches such as the preselectors. group selectors, etc. inrolved in the talking connection. is ettccted in the manner hereinbctore described.

In cases in which a calling subscriber who has been connected through to the trunk 301, 302, wishes to connect to another subscriber belonging to the same board, i. e. to another subscriber connec'ed to the contact bank brushed over by the wipers 353, 854. 355, 356, 357, Fig. 10, he will send in two or more dialling impulses to operate the tens designating switch Td and this will result in the wipers 35S, d170, 4:71, 3172 being stepped round two or more. say three, steps. The arcuate wiper 358 will then leave the contact sac and establish connection with the bank contacts 359, 380 before the contact 491v is closed during the pause between the penultimate and the last series of dialling impulses. Hence, no test current will flow through 280, 358, s00, .01 and through the testrelay 79, so that the talking current wipers 472, 471 of the designating switch will remain dead in any case. On the other hand negative battery will be applied from 480. through 358 to the bank contacts touched by the arcuate wiper 358 and the operating magnet 374: of the wipers 353, 357 will rotate these wipers and cause them to be set scriber responds the relay 34-2 will be enerd and will cut off the ringing relay S t-7 and connect the calling subscriber through to the wanted line. The restoration of the designating switches T61, Ud and of the main switch wipers 353-857 also effected in the manner hereinber'ore described.

Only slight changes of the circuits of Fig. 10 are required to adapt them for trunking to another board by means of several trunks, instead of by one outgoing trunk only. These changes are indicated in Fig. 11 which represents the right part of Fig. 10 with the required alterations. the left part being omitted as it would be precisely similar to the corresponding left part of Fig. 10. An inspection of 11 will show that the said alteration consists 1 in omitting the test wire 492 of Fig. 10 with the associated resistance 4:03. 2 in providing a single arcuate bank contact 497 instead of two contacts as? and 473, Fig. 10, and 3 in running a separate trunl' 4-76. 1-77 from each tens designating switch, instead of having a single trunk 476, 477 multipled over all of the tens designating switches Td of the selector group.

When the wipers 472. 4:71, s are rotated one step by a single dialling impulse; that afiects the magnet the relay which does not act as a test relay in this case, is energized and connects the calling subscriber through the trunk 4:76, 477 which is connected at the line finders of the second board like an ordinary subscribers line. The trunk L76, $77 is then connected by an idle line finder to a numerical switch through which the conversational circuit is established in the manner described in connection with Figs. 3, 4 and 5.

The restoration of the switches after the conversation is also efiected as already explained in connection with Fig. 10.

From the foregoing description it will be apparent that in an arrangement according to Fig. 10 the inter-exchange or inter-board trunk 470, 477 multipled over the tens designating switches and also over the line finders at the second board, while in an arrangement according to Fig. 11 the interboard trunks each emanate separately from a designating switch Td and are multipled over the line finde s at the second board only.

Fig. 12 shows the circuits of a final selector according to Fig. 5 modified for intergroup or inter-exchange trunk working, only such of the circuits being shown as are deemed necessary for a clear understanding of the inter-exchange trunking operations. The final selector corresponds in all details to that hereinbetore described except that a wiper 500, a relay contact 501, a relay contact 550, and a row of bank contacts amongst which are 502, 503, 504s are added. Such of the parts of the final selector as are deemed necessary to enable the operation to be understood have signs of reference that correspond to those used in the figures hereinbetore described except that an index 2 is added to them.

It is assumed that the first three lines 505, 506507, 508509, 510 leading from the contact bank of the selector are trunks lead ing to another exchange or board. At the second board 600 these trunks are multipled over the bank contacts of line finders similar to those hereinbet'ore described. Also connected to the bank contacts of these finders (not shown) are ordinary subscribers lines, as line 110 111.

The arrangement of the connector or final selector 400 in the first board is such that when its wipers 353 354 500, 350 357 are set onto a trunk, as 505. 506 leading to the second board, these wipers will more from one trunk to another until a tree trunk is found. For each such group of interboard or inter-exchange trunks there is a set of bank contacts 502, 503, 504 all of which are connected to the negative pole of the battery as shown, except the last contact 50a of the set, which is dead. These contacts with their cooperating wiper 500 form a part of the :means by which the wipers of the con rector 500' caused to rotate until an idle one of a set of equivalenttrunks 505, 506- 507, 508509, 510 is found.

The wiring and equipment of the 1nterboard trunks differs slightly at the second board 600 from that or" the subscribers lines 110 111 the trunks being each provided with an alternating current relay 527, condenser 552 is connected in parallel to the relay 103 so as to provide a by-path of low resistance for the alternating currents by which the alternating current line relays 527;

of the inter-board trunks are energized.

The line finder starting Wire 11'!- and the "return-impulse-Wire 126 at the. board 600 correspond to similar wires 117 and 126 of Fig. 3 hereinbefore described. The branch Wires 172 177 are connected to a set of:

bank contacts of the line finders (not shown) at the second board 600.

The inter-board trunks 505, 506507,

508-509,'510 are two-way trunks and are connected at both boards to the bank contacts of final selectors,'as 400, and of line finders, the wires 511. 512, 513 being the normals that are inultipled over the banks of the line finders of the first board, andthe wires 514, 515, 516 being'the nornialsthat lar to the finders of Fig. 3, setting'its wipers onto the calling trunk. The operation of the circuits and apparatus shown in Fig; 12 will now be described in detail.

It will be assumed that a subscriber connected to the first board desires a connection with a subscriber connected to the second board. i

The calling subscriber es'ablishes a connection with an idle final selector, as 400, in the manner hereinbetore described and the impulse relay 303 in this selector will then he energized. The calling subscriber then sends two series of dialling impulses into the final selector, whereby its tens and units designating switches are. set and its .wipers 353 354 355 500. 35? are guided onto the first trunk 506 of the set of trunks leading to the desired boards. There may, of course, be two or more diflerent be rds accessible throughthe final seiec- W0. l i hen the trunk 505, 506 is reached the relay 377 is energized and the test circuit through the test relay 395 is closed. All the'operations up to this point are similar to those l'iereinbeioij'c described 'so that it is not deemed necessary to repeat this description here.

It, the first trunk line 506, 505 is free the/test relay 395 will be energized and it will open the circuit of the operating magnet 3H at 501, but it this trunk is'eiigaged the. relay 395 will not be energized and the magnet 3749 will receive current iii'ipulsestliat flow tron'ithe positive pole throi'igh the interrupter 375 375?, 501, wiper 500, bank contact 502 to the positive pole, The movement of the wipers will continue either until a free trunk is reached or until the wipers land on thelast trunk or the group, when the wiper 500 will touch a dead contact 504 so that impulses will cease flowing through 500, 501, magnet 374*, 375

to the positive pole of the battery and the wipers will stop. The calling subscriber will then receive a busy signal in the ordinary way. I

It will now be assun'iedtliat the first trunk 505, 506 isfree. The test relay 395 \vill then be energized, as soon as the wipers of the connector reach this trunk, by a current which flows from the negative pole through 393 395?,355 test wire 513, cut-off relay (not shown) associated with the normals 511, 512 at the line finders (not shown) of the first board to the positive pole. The said cut-cit relay and line finders are ar ranged like the relay 109" at the second board 600 and like the finder 100 of Fig. 3. The test relay 395 immediately renders the trunk 505, 506, busy at the first board by short-circuiting a part of its winding and thus reducing the 'iotential" on the test wire 513. and at the same time closes he circuit o't'the ringing relay 3M and thus sends alternatii'ig current through the line relay 527 atthe second board, this alternating current flowing from the ringing current generator 3416 through 3&9, 401 53 505, 520, condensers 551, 527 523 and all the similar contacts of the relays oi the other trunks and subscribers l nes of the same group,

condenser battery, earth, 518, 506, 354- 400 3 15 'rin in current enerator 340 9 7 g b h The line relay 527 responds and closes its contacts 526 and 529 so as to energize the line finder starting relay 103 and the auxiliary line relay 530, which latter receives current through the resistance 528 and attracts its easily moved armature so as to close the contact 525 and: Open contact 523. The 

